Research On Spatial Effect Of Stiffening Steel Box Girder Of Wide Cable-stayed Bridge

In order to meet the requirements of modern transportation,the bridge structure with large span and ultra-wide diameter is widely used in bridge design.The oblique pull bridge is widely used because of its smaller beam body bending moment,lighter structure self-weight,good span ability and beautiful shape.In this paper,based on the engineering background of the Jinhai Bridge,the vertical bridge of the wide-frame reinforced steel box beam is studied with the force of the vertical bridge and the law of spatial deformation.The main research contents and conclusions are as follows:(1)The finite element model of the original bridge segment was established by the finite element software ANSYS,and the normal stress along the bridge under the constant load,the most unfavorable unilateral live load and the most unfavorable symmetric live load during the completion stage of the cable-stayed bridge was systematically analyzed.The distribution law in the longitudinal direction.The results show that under the three load conditions,the spatial effect of the longitudinal normal stress distribution of the roof and floor plates is obvious,and they are all under compression.The normal stress change law along the longitudinal bridge direction where the inner and outer webs meet the top plate is basically similar,and every12m(cable spacing)along the longitudinal bridge direction is a change period;the pressure on the inner web is greater than the outer web at the same position The pressure on the board.The maximum normal stress occurs at the position where the inner web and the top plate intersect;where the inner and outer webs and the bottom plate meet,the normal stress change law along the longitudinal bridge direction is basically similar,and both are under pressure and the pressure difference is small.The eccentric load will obviously increase the compressive effect of the local area.Under the full load condition,the normal stress value of the live load action area is obviously larger than that under the constant load condition.(2)Through the finite element software method,systematically analyzed the spatial deformation distribution law of the structural main girder under constant load,unilateral live load and symmetrical live load: the deformation of the wide steel box stiffened beam arm end is the most under the three working conditions.Obviously,the segmental deformation between the outer webs on both sides is not obvious.Under the action of symmetrical load,the application of live load is unfavorable to the vertical deformation of steel box stiffened beam.The eccentric load is unfavorable to the torsional deformation of the steel box stiffened beam.(3)In order to more accurately grasp the working performance of the bridge structure,a scaled model test of the structure was carried out according to the principle of model test design,combined with the structure structure of the research object and the actual test conditions.The five aspects of test model design,production,calculation and analysis,test loading and testing are discussed.(4)According to the model test and the comparative analysis of theory and experiment,the law of spatial deformation effect of wide steel box girder under different load combinations is studied and analyzed,and the correctness of the theoretical analysis method is verified.The results show that under the action of eccentric load and symmetrical full-load live load,the deflection of different sections along the longitudinal direction of the main girder changes linearly,and the deflection deformation is distributed asymmetrically on the cross section.The downward deflection of the arm is relatively larger.